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I will assume that each subsequent cross blocks line of sight to the one in front it, otherwise obviously it's the last one.

Can they talk and are we under assumption that they individual objective is getting free?

It is some kind of Dirichletan puzzle, since we have finite pool, so if communication for us is not practical, try to think along ways of knowing for sure what the backsides of 4 crosses are to eliminate them and learn the only possibility left.